REGULATORY CHARACTERISTICS OF A FRUCTOSE BISPHOSPHATASE FROM THE BLUE-GREEN BACTERIUM ANACYSTIS-NIDULANS

A specific fructose 1,6-bisphosphatase (EC 3.1.3.11) has been partially purified from the obligately autotrophic blue-green bacterium Anacystis nidulans. It was most active at pH 8.0. The Km for fructose 1,6-bisphosphate was 0.088 mm at pH 8.0 and 0.105 mm at pH 7.0; the Km for MgCl2 was 0.95 mm at pH 8.0. Activity at netural pH was particularly sensitive to the MgCl2 concentration. AMP was an allosteric inhibitor, 50% inhibition being exerted by 0.058 mm AMP at pH 7.0 and 0.085 mm AMP at pH 8.O. The way in which changes in intracellular pH and the concentrations of Mg2+ and AMP might influence the activity of the enzyme in the Calvin cycle, the oxidative pentose phosphate pathway and in glycolysis and gluconeogenesis is discussed. © 1979.